I believe that you should calibrate your center channel to be the same as your fronts. Often times, people turn their surrounds up too loud. The surrounds aren't always in use (there's no material in the soundtrack sent to them). The surrounds, when used properly, should add to the soundstage, not overtake it or become obvious or distracting. It's good that your front three speakers are by the same manufacturer...they should blend seamlessly.
Happy tweaking !!!